Heat exchanger construction



March 31 1964 F. BONI, JR., ETAL 3,126,949

HEAT EXCHANGER CONSTRUCTION Filed July 5, 1959 6 Sheets-Sheet 1 INVENTORS FmrkBazmJz:,P 610% By amlDonaldL wmmel FMM f ATTORNEYS March 31, 1964 F. BONI, JR. ETAL 3,126,949

HEAT EXCHANGER CONSTRUCTION Filed July 3, 1959 6 Sheets-Sheet 2 IN V EN TORS Mmmmz' 9.0m BY zmdDanalJL. wmmel es gxtaaaqwavukw ATTORNEYS March 31, 1964 F. BONI, JR.. ETAL HEAT EXCHANGER CONSTRUCTION 6 Sheets-Sheet 3 Filed July 3, 1959 INVENTORS FmdzBondJnP 510%! By MDOIWML- ammel ATTORNEYS March 31, 1964 F. BONI, JR., ETAL HEAT EXCHANGER CONSTRUCTION 6 Sheets-Sheet 4 Filed July 5, 1959 INVENTORS FmBmJnPkil' 5 BY amlDanaldL. ummel ATTORNEYS March 31, 1964 F. BONI, JR., ETAL 3,126,949

HEAT EXCHANGER CONSTRUCTION Filed July 5, 1959 6 Sheets-Sheet 6 INVENTORS Ha/nkBanJr Ph/ih 61055911 BY amtDomML. ummeb ATTORNEYS United States Patent 3,126,949 FEAT EXCHANGER CQNSTRUCTION Frank Boni, Jr., Massillon, and Philip S. (itten and Donald L. Hummel, Canton, Ohio, assignors, by mesne assignments, to Baldwin-Lima-Hamiiton Corporation, Philadelphia, Pa, a corporation of Pennsylvania Filed July 3, 195?, Ser. No. 824,861

11 Claims. (Cl. 165-1538) Our invention relates to improvements in heat exchanger constructions and more specifically to heat exchanger constructions preferably for use as steam generators. Even more specifically, our invention relates to heat exchanger constructions having improved heat transfer efficiency in a heat exchanger of minimum size and particularly with high-temperature differentials.

Many problems have been encountered in prior constructions of heat exchangers, one of which may be present where spaced tube sheets are provided in a heat exchanger shell supporting the inlet and outlet ends of straight tubes. In such prior construction, when major temperature differentials are encountered between the inlet and outlet temperatures of the fluids passing through the tubes, these temperature differentials cause the straight tubes to expand, thereby causing the straight tubes to bow and sometimes fail.

This problem has been somewhat minimized by the use of a single tube sheet with U-shaped tubes, so that the same tube sheet supports both the inlet and outlet ends of the tubes. Thus, since the U-shaped ends of these tubes are free, the tubes are therefore free to expand and contract under the high-temperature differentials.

This prior construction, however, creates a new problem, that is, the setting up of high stresses in the single tube sheet between the portions of the tube sheet supporting the inlet ends of the tubes and the portions of the tube sheet supporting the outlet ends of the tubes, again where major temperature differentials are encountered. This problem becomes particularly critical in modern heat exchanger applications because of the higher and higher temperatures and pressures required.

A further problem encountered in prior heat exchanger constructions is the desire to provide a maximum of heat transfer area. This results in the number of the tubes being greatly increased as well as, of course, the number of tube connections to the tube sheets. With the greater number of tubes and tube connections, the velocity of the fluid passing through the tubes and heat exchanger shell has been decreased, although the total volume of the tubes has been increased, thereby reducing the heat transfer efficiency of the constructions.

Still further, this increase in the number of tubes in an effort to provide a maximum of heat transfer area has resulted in the heat exchanger shells increasing to prohibitive sizes.

It is, therefore, desirable to provide a heat exchanger construction having a minimum number of tubes and tube connections in order to maintain a high fluid velocity through the tubes and shell, resulting in a maximum of efficiency, yet to provide a maximum of heat transfer surface with this smaller number of tubes in a minimum of shell volume.

It is also necessary, with the maximum of heat transfer surface using the minimum number of tubes and tube connections, to maintain the tubes properly spaced so that the fluid entering the shell chamber and circulating around the tubes properly contacts all of the tube surfaces evenly in order to derive the maximum of heat transfer. For this reason, it is desirable to maintain the tubes evenly spaced and to direct the fluid into the shell chamber and against the tubes in such a manner that contact with all 3,l2fi,9i9 Patented Mar. 31, 1964 of the tubes will be even and complete, despite the particular configurations of the tubes necessary in order to provide the maximum of heat transfer surface.

Finally, it is desirable in a heat exchanger, particularly Where the two fluids involved are at temperatures or of compositions which result in possible explosion upon contact between the two fluids within the heat exchanger, to provide some portion of the exchanger at all times in communication with at least the portions of the shell chamber enclosing the tubes which is properly designed for rupture in the event of such interleakage and explosion. This will prevent damage to the major portion of the shell and eliminate the possibility of major destruction thereof.

It is, therefore, a general object of the present invention to provide a heat exchanger construction which overcomes the problems and diificulties hereinbefore discussed.

It is a primary object of the present invention to provide a heat exchanger construction which has a maximum amount of heat transfer area on the heat exchanger tubes, yet this heat transfer area is provided with a minimum number of tubes in a minimum of shell volume.

It is a further object of the present invention to provide a heat exchanger construction which incorporates a tube bundle which is formed from involuted serpentinetype tubes.

It is still a further object of the present invention to provide a heat exchanger construction in which the tube bundle includes a series of tubes, each having a straight tube section connected through an involuted section to an involuted serpentine-type section.

it is an additional object of the present invention to provide a heat exchanger construction in which separate ring-like inlet and outlet tube sheets are incorporated permitting greater inlet and outlet temperature differentials.

It is also an object of the present invention to provide a heat exchanger construction in which the tubes are mounted for relatively free expansion within the shell without creating undue stresses therein.

It is a further object of the present invention to provide a heat exchanger construction in which the tube bundle is formed for an even flow of shell fluid thereover, thereby resulting in the maximum of heat transfer efficiency.

It is another object of the present invention to provide a heat exchanger construction in which a minimum number of tubes and tube connections are used resulting in less resistance and greater fluid velocity, again providing a maximum of heat transfer emciency.

it is still another object of the present invention to provide a heat exchanger construction in which a portion of the shell is designed to properly rupture in the event of malfunction within the shell, thereby minimizing any possible dangers of such malfunctions.

Finally, it is an object of the present invention to provide a heat exchanger construction which satisfies all of the above ob ects, yet is formed for a maximum of efficiency in assembly thereof.

These and other objects are accomplished by the parts, constructions, arrangements, combinations and subcombinations comprising the present invention, the nature of which is set forth in the following general statement, a preferred embodiment of whichillustrative of the best mode in which applicants have contemplated applying the principles-is set forth in the following description and illustrated in the accompanying drawings, and which is particularly and distinctly pointed out and set forth in the appended claims forming a part hereof.

The heat exchanger construction comprising the present invention may be stated generally as including a heat exchanger shell forming a shell chamber and preferably positioned extending generally vertically with a shell fluid outlet at the lower portion of the shell communicating with the shell chamber and with a shell fluid inlet at an upper portion of the shell communicating with the shell chamber. Further, the construction includes tube sheet means in the form of preferably ring-like tube sheets spaced longitudinally of the shell from each other or spaced vertically when the shell is posi ioned extending vertically, with one ring-like tube sheet preferably general ly having an outer diameter no larger than the inner diameter of the other but spaced longitudinally therefrom.

Still further, the construction includes a first bank of tube sections connected to one of the tube sheets and extendin longitudinally within the shell, and a second bank of tube sections connected to the other tube sheet and extending at least partially in combined involuted and serpentine paths and overall in a longitudinal direction within the shell opposite from the direction of extension of the first bank of tube sections. These two banks of tube sections are connected at an end of the shell opposite from the end mounting the two tube sheets by means of involuted laterally extending tube sections so that from the first bank of tube sections, the tubes extend involuted laterally, then progressively longitudinally, then again involuted laterally, then longitudinally and so forth, to form the second bank of involuted serpentine tube sections.

It is preferred that the first bank of tube sections is composed of straight longitudinally extending tube portions, and this first bank may be separated from the second bank by an insulating wall, with the banks of tubes being ring-like in lateral cross section and one telescoped within the other. Thus, due to the involuted lateral connections between the first and second banks of tube sections and the involuted serpentine configuration of the second bank of tube sections, all portions of the tubes are maintained evenly spaced at all times and provide a maximum of heat transfer surface and efliciency.

Still further, the heat exchanger construction is formed with the shell fluid inlet directing fluid over the involuted serpentine bank of tubes; and at the location of the shell fluid inlet, this second bank of tubes is formed with straight longitudinally extending tube sections so that the fluid entering the shell may first circulate or pool around the straight longitudinally extending tube section before passing over the involuted serpentine section, thereby providing an even flow of fluid over the involuted serpentine section.

Also, with the heat exchanger construction formed with the involuted serpentine bank of tube sections at the outer portions of the shell and the first straight bank of tube sections telescoped and laterally inwardly of this involuted serpentine bank, the entire tube bundle may be surrounded at spaced longitudinal locations with tube assem bly bands which are designed to expand and contract freely in a circumferential direction a predetermined amount. Finally, with the heat exchanger construction extending generally vertically, the shell is provided with a rupture disc at the upper portion thereof preferably above the ring-like tube sheets and communicating with the shell portions enclosing both banks of tubes for rupturing in the event of malfunction within the heat exchanger shell.

By way of example, an embodiment of the heat exchanger construction of the present invention is illustrated in the accompanying drawings forming a part hereof, wherein like numerals indicate similar parts throughout the several views, and in which:

FIG. 1 is a fragmentary vertical sectional view, part in elevation, of the complete heat exchanger assembly with the tube bundle being represented in broken lines;

FIG. 2, an enlarged fragmentary vertical sectional View, part in elevation, taken from the upper portion of FIG. 1;

FIG. 3, an enlarged fragmentary vertical sectional view, part in elevation, taken from the central portion of PEG. 1;

FIG. 4, an enlarged fragmentary vertical sectional view, part in elevation, taken from the lower portion of FIG. 1;

FIG. 5, an enlarged sectional view, part in elevation, looking in the direction of the arrows 55 in FIG. 1;

FIG. 6, an enlarged fragmentary sectional view, part in elevation, looking in the direction of the arrows 6-6 in FIG. 1;

FIG. 7, an enlarged fragmentary sectional view, part in elevation, looking in the direction of the arrows 77 in FIG. 1;

FIG. 8, an enlarged fragmentary sectional View, part in elevation, looking in the direction of the arrows 8-8 in FIG. 1;

FIG. 9, a fragmentary sectional view, part in elevation, looking in the direction of the arrows 99 in FIG. 5;

FIG. 10, an enlarged fragmentary sectional view, part in elevation, looking in the direction of the arrows 1(llll in FIG. 5;

FIG. 11, a top plan view of one of the tube bundle bands removed from the remainder of the heat exchanger construction;

FIG. 12, an enlarged fragmentary side elevation, looking in the direction of the arrows 12l2 in FIG. 11; and

FIG. 13, an enlarged fragmentary sectional view, part in elevation, looking in the direction of the arrows 13-43 in FIG. 11.

The particular embodiment of the heat exchanger construction of the present invention shown in the drawings is for use principally as a steam generator with water flowing through the tube bundle and being transformed therein into steam by a heating medium, such as liquid sodium, circulating through the heat exchanger shell. It should be understood, however, that the particular embodiment shown is not intended as a limitation, and the principles of the present invention can be applied to many forms of heat exchangers with slight modification, if any.

As shown in FIG. 1 of the drawings, the embodiment of the heat exchanger shown in the drawings includes a heat exchanger shell, generally indicated at 20, preferably generally hollow cylindrical in configuration and forming the shell chamber, generally indicated at 21. The shell 26 is preferably positioned with its longitudinal axis extending generally vertically and having a pair of laterally oppositely disposed fluid inlet connectors 22 formed in the hollow cylindrical shell side wall 23 intermediate the height thereof and communicating with the shell chamber 21.

. The lower end of shell 29 is provided with a lower head 24 connected to and extending downwardly from the side wall 23 and mounting centrally thereof a shell fluid outlet connector 25, likewise communicating through the lower head 24 and with the shell chamber 21. A series of mounting flanges 26 are connected to the outer shell side wall 23 intermediate the height of this side wall, as shown in FIG. 1, and these mounting flanges 26 are for use in supporting the heat exchanger construction in a desired steam generating installation in a conventional manner.

Mounted at the upper end of the shell side wall 23 and extending generally laterally or radially inwardly is the ring-like steam manifold plate 27 which is connected to the side wall 23 by a ring of bolts 28 and preferably abuts the side wall 23 in a tongue and groove connection, as indicated at 29. The steam manifold plate 27 terminates laterally or radially inwardly in a central opening 39, and this plate at the upper surface 31 is provided with the longitudinally extending and laterally or radially spaced ring-like flanges 32 and 33.

Overlying the flanges 32 and 33 is the laterally extending ring-like steam manifold cover 34 which is secured to the flanges 32 and 3'3 by means of a ring of bolts 35 secured to the flange 32 and a ring of bolts 35a secured to the flange 33. Thus, a closed steam manifold 36 is defined by the steam manifold plate 27, the flanges 32 and a) 33 and the manifold cover 34, and the usual tube outlet connectors 37 and 36 are mounted on the manifold cover 34- in communication with the manifold 36 through the manifold cover 1%.

A hollow cylindrical extension 39' is connected to the steam manifold plate flange 33 extending longitudinally upwardly laterally inwardly of cover 34 and terminating spaced thereabove at the water manifold plate 40 and preferably integrally therewith. The water manifold plate 46, similar to the steam manifold plate 27, is generally ring-like in configuration extending laterally inwardly from the extension 39 and terminating laterally inwardly in the circular opening 41.

Also, similarly, the longitudinally upwardly extending later-ally spaced ring-like flanges 42 and 46 are mounted on the water manifold plate upper surface 44 and receive the laterally extending ring-like water manifold cover 45 thereover, forming the ring-like water manifold 46. The manifold cover 45 is likewise retained on the flanges 42 and 43 by the ring of bolts 47 received in the flange 42 and the ring of bolts 48 received in the flange 43, and this cover mounts the tube inlet connector '49 thereon communicating through the cover with the water manifold 46.

Thus, the members forming the steam manifold 36 extend laterally or radially outwardly from the extension 39, and the members forming the water manifold 46 extend radially or laterally inwardly from extension 39, so that the water manifold 46 has an outer diameter generally not greater than the inner diameter of the steam manifold 36 and is spaced longitudinally or vertically therefrom. Further, a liquid level probe tube 50 may be mounted extending longitudinally through the steam manifold plate 27 laterally outwardly of the steam manifold 36 and flange '32, as shown, for its usual purpose.

A hollow longitudinally extending generally conicallyshaped extension 51 is connected to the water manifold flange 43 and extends longitudinally upwardly, laterally inwardly of the Water manifold cover 45. Extension 51 is connected at its upper end to the lower rupture disc flange 52.

Mounted abutting the top surface of flange 52 is a lower rupture disc gasket 53 which connects with an overlying upper rupture disc gasket 54- in tongue and groove fashion, as shown at 55. Mounted between the gaskets 53 and 54 and beginning at the tongue and groove connection 55 is the upwardly dished rupture disc 56 having the shape of a spherical sector, as shown, which is a solid disc extending across the top of the lower rupture disc gasket 53 and closing the upper end of the shell chamber 2-1.

The upper rupture disc flange 57, as shown in FIG. 2, overlies the gasket 54, with the flanges 53 and 57 retaining the rupture disc 56 and gaskets 53 and 54 in assembled position by means of a ring of bolts 58. Finally, a genenally hollow cylindrical extension 59 is mounted on the upper rupture disc flange 57 extending upwardly and mounting the usual connecting flange 6!).

A generally hollow cylindrical shroud extension 6-1 is attached abutting the inner cylindrical surface of the steam manifold plate 27 within the opening 36 and extending longitudinally downwardly of plate 27. This shroud extension 61 is mounted in place by means of the connecting flange 62 extending laterally outwardly from the shroud extension 61 and beneath the lower lateral surface 63 of the steam manifold plate 27. Connecting flange 62 may be secured to the steam manifold plate lower surface 6 3 in any usual manner, such as a series of bolts 64, and retains the shroud extension 61 extending longitudinally downwardly a distance below the steam manifold plate 27.

A generally hollow cylindrical shroud is connected to the lower end of the shroud extension 61 and is formed by the laterally spaced and telescoped hollow cylindrical shroud members 65 and 66. Shroud members 65 and 66 extend longitudinally downwardly generally parallel to the shell side wall 23 and spaced laterally inwardly therefrom to within a short longitudinal distance from the shell lower head 24, as shown. Further, these shroud members 65 and 66 are maintained laterally spaced at the lower ends by the spacers 650, shown in FIG. 4.

Thus, the shroud members 65 and 66 divide the shell chamber 2 1 into an inner shell chamber 67 and an outer shell chamber 68, and in View of the shroud being formed by the laterally spaced hollow cylindrical shroud members 65 and 66 forming a dead air space therebetween, these shroud members also form an insulating Wall between these inner and outer shell chambers 67 and '68, the purpose of which will be hereinafter explained. Furthermore, the shroud extension 61 is provided with a series of openings 6 9 formed therethrough and communicating between the outer shell chamber 68 and the inner shell chamber 67.

A generally hollow cylindrical tube bundle, generally indicated at 70, is positioned partially within the inner shell chamber 67 and partially within the outer shell chamber 68, and telescoped over the shroud members 65 and 66 and the shroud extension 6-1. Tube bundle 70 is formed by a series of preferably straight downcomer tube sections 71 which are connected through the water manifold plate 46 communicating with the water manifold 46, and extend longitudinally downwardly within the extension 39, the members forming the steam manifold 36 and adjacent the inner side of the shroud extension 61 and shroud member 66.

The downcomer tube sections 71 are supported in the inner shell chamber 67 by a series of longitudinally spaced ring-like support plates 72 in usual fashion, which support plates are supported within the inner shell chamber 67 by the usual tie rods 73. Tie rods 73 are connected to the lower surface 74 of the water manifold plate 40 laterally inwardly of the downcomer tube sections 71 extending longitudinally downwardly between the support plates 72 and maintaining the support plates preferably spaced laterally inwardly of the shroud member 66.

Downcorner tube sections 71 extend longitudinally downwardly below the lower ends of the shroud members 65 and 66 and are supported inwardly of the shroud member 66, spaced longitudinally upwardly from the lower end of this shroud member, by a laterally extending ringlike support plate 75, which is secured to the shroud member 66 extending laterally inwardly therefrom. Spaced below the lower ends of the shroud members 65 and 66, the downcomer tube sections 71 are connected through laterally outwardly extending involuted tube sections 76 to the laterally and longitudinally upwardly extending involuted serpentine tube sections 77, within the outer shell chamber 68.

Connected at the inner end of the support plate 75, spaced laterally inwardly from the downcomer tube sections 71 and extending longitudinally from support plate 75 to below the involuted tube sections 76, is the hollow support cylinder 78. Cylinder 78 is provided with a series of openings 79 laterally tlrerethrough and at its lower end is closed internally by the laterally extending end plate 86, which plate also has a series of openings 81 longitudinally therethrough.

A laterally extending spider plate 82 is telescoped over the lower end of the support cylinder 78 and extends laterally outwardly from this support cylinder spaced below the involuted tube sections 76. As shown in FIG. 8, the spider plate 82 is formed with an inner hollow cylindrical portion 83 directly surrounding the support cylinder 78 and a series of circumferentially spaced laterally extending spider fingers 84 extending laterally outwardly from cylindrical portion 83. Also a ring-like spider plate flow baflle 85 is mounted on the cylindrical portion 83 spaced laterally outwardly from the support cylinder 78 and extending longitudinally upwardly to within a short distance of the involuted tube sections 76, as shown in FIG. 4, and the cylindrical portion 83 is provided with a series of openings as longitudinally'therethrough laterally inwardly of the battle 85.

As will be hereinafter further discussed in detail, the involuted serpentine tube sections 77, within the outer shell chamber 63, extend progessively longitudinally upwardly in a series of outer longitudinally extending portions 87, connected to involuted laterally inwardly extending portions 88, connected to inner longitudinally extending portions 89, connected to involuted laterally outwardly extending portions 90, which are again connected to another series of outer longitudinally extending portions 87, and so forth, longitudinally upwardly within the outer shell chamber 68, as shown. The involuted serpentine tube sections 77 terminate the involuted and serpentine paths spaced below the shell inlet connectors 22 and spaced laterally outwardly from the shroud member 65, where these tubes preferably extend as straight longitudinally extending tube sections 91 longitudinally by the shell inlet connectors 22 to the steam manifold plate 27.

The straight tubes 91 are connected through the steam manifold plate 27 in communication with the steam manifold 3 6, as shown in FIGS. 1 and 2. Thus, the involuted serpentine tube sections 77 extend longitudinally upwardly within the outer shell chamber 68 to the shell inlet connectors 22 and then are preferably connected to the straight tube sections 91 for the remainder of their extension longitudinally through the outer shell chamber 68, with any desired number of the involuted serpentine convolutions being used for the required heat transfer of the heat exchanger construction.

The involuted serpentine tube sections '77 are supported within the outer shell chamber 63 by a series of truss rods 92 connected to the inner and outer support rings 93 and 94, which in turn are connected to the series of inner and outer support bars 95 and 96-. As shown in FIGS. 1, 2 and 9, the truss rods 92 are connected in longitudinally downwardly V-shaped pairs to the lower surface 63 of the steam manifold plate 27 laterally outwardly of the straight tube sections 91.

In the general longitudinal location of the lower portion of the shell inlet connectors 22, each of these truss rods 92 is connected through the laterally extending attachment plates 97 to the outer and inner support rings 93 and 94. Inner support ring 94 is telescoped within and spaced laterally inwardly from the outer support ring 93, with the attachment plates 97 extending laterally between these rings and with the lower ends of the truss rods 92 attached to the attachment plates 97 laterally intermediate and spaced from each of the outer and inner support rings 93 and 94, as shown in FIGS. 1, 3 and 9.

The outer support ring 93 is spaced laterally inwardly from the shell side wall 23, and the inner support ring 94 is spaced laterally outwardly from the straight tube sections 91. A series of longitudinally extending outer support bars 95' are connected to the outer support ring 93, and a series of longitudinally extending inner support bars 96 are connected to the inner support ring 94, with these support bars extending longitudinally downwardly generally parallel to the shell side wall 93 to below the involuted tube sections 76 adjacent the shell lower ead 24.

As best shown in FIGS. 3, 4 and 10, each of the support bars 95 and 96 receives a longitudinal row of the involuted serpentine tube sections 77 therethrough at each of the laterally inwardly and laterally outwardly extending portions 88 and 89, so that the outer support bars 95 extend longitudinally downwardly laterally inwardly of the outer longitudinally extending portions 87, and the inner support bars 95 extend longitudinally downwardly laterally outwardly of the inner longitudinally extending portions 89. The involuted serpentine tube sections 77 are received relatively loosely through these outer and inner support bars 95 and 96 to permit slight movement under expansion and contraction. of these 8 tube sections, but these support bars and 96 through their attachments with the steam manifold plate 27, as described above, securely support these involuted serpentine tube sctions 77 within the outer shell chamber 68.

Connected to the lower ends of the outer support bars 95 is the outer support ring 98, and similarly connected to the support bars 96 is the inner support rings 99, with these support rings 98 and 99 being generally laterally aligned with the spider plate $2. Furthermore, outer support ring 98 is maintained laterally spaced from the inner support ring 99 by the circumferentially spaced laterally extending spacing bars 1%, as best shown in FIGS. 1, 4 and 8.

Each of the outer support rings 93 and 93 at the upper and lower portions of the shell is maintained properly laterally spaced from the shell side wall 23 by the ring sectors 191 which extend laterally outwardly from the support rings 93 and 98 and mount the resilient spring members 102 which merely laterally abut the shell side wall 23, as shown in FIGS. 1, 3, and 4. Further, the inner support ring 99 at the lower portion of the shell is maintained laterally positioned by abutment laterally inwardly with the outer lateral extremities of the spider plate fingers 84, which fingers are received in slots 163 formed on the inner circumferential surface of the inner support ring 99 in lateral alignment with the spacing bars 1%, as shown in FIGS. 1, 4 and 8.

Thus, a shell fluid path is provided through the outer shell chamber 68 from the shell inlet connectors 22 down over the outer and inner support rings 93 and 94, over the involuted serpentine tube sections 77 between the outer and inner support rings 98 and 99, as well as between the spider plate fingers 8'4 to the shell lower head 24 and outwardly through the shell outlet connector 25, as will be hereinafter explained more in detail.

As shown in FIGS. 1, 3 and 4, a series of longitudinally spaced tube bands 194 is positioned surrounding the involuted serpentine tube sections 77 at the outer circumference of the tube bundle 70. One of these tube bands 194- is positioned aligned laterally outwardly at each of the groups of inner longitudinally extending portions 89 of the involuted serpentine tube sections 77 and longitudinally spanning the distance between the longitudinally spaced groups of outer longitudinally extending portions 87 of these tube sections 77.

As shown in FIGS. 11, 12 and 13, each of the bands 164 is formed in three substantially identical band segments 105, with each band segment having a longitudinal cross-sectional shape, as shown in FIG. 13, comprised of the longitudinally spaced and generally longitudinally extending engagement portions 106 connected to the central laterally inwardly extending generally U-shaped abutment portions 107. Mounted within each of the U-shaped abutment portions 107 at spaced circumferential intervals are the roller sockets 198, each enclosing a roller 199.

Each of the rollers 1119 is positioned within its particular roller socket 198 freely rotatable and extending laterally outwardly beyond socket 1113 and the tube band engagement portions 106. Finally, each of the band segments 105, as shown in FIG. 12, has mounted at an end portion thereof within the abutment portions 197 a connecting bar 119 having a slot 111 formed therein and receiving a pin 112 mounted in the end portion of the next adjacent band segment 1115.

Thus, the tube bands 1114 are engaged around the involuted serpentine tube sections 77, as described above, with the engagement portions 1% engaged with longitudinally adjacent outer longitudinally extending portions 87 of these tube sections and with the band abutment portions extending slightly laterally inwardly longitudinally between longitudinally adjacent laterally inwardly and laterally outwardly extending portions 88 and 913 of these tube sections. When the tube bands 194 are so positioned, with the tube bundle '70 within the shell 29, these tube bands are maintained slightly compressed so that the rollers 109 abut against the shell side wall 23 and the pins 112 are intermediate the lengths of slots 111 in the connecting bars 110.

In view of this particular construction, these tube bands 104 may be placed around the tube bundle 70 in their proper appropriate positions, and the tube bundle inserted into the shell 29. As the tube bundle 70 is compressed laterally inwardly and permitted to expand laterally outwardly during this insertion process, because of the particular construction of these tube bands 104, they will permit the tube bundle to come and go laterally, and the bands will likewise compress and retract as required. Also, when these tube bands 104 have reached their final longitudinal location, if the shell side wall 23 is slightly out of round in any of these locations, the bands 104 and the tube bundle 70 will be permitted to expand or contract as necessary to substantially conform to the shell side wall 23.

The particular configurations of representative groups of the tubes in the generally hollow cylindrical tube bundle 70 are shown clearly in FIGS. 1 through 7. As before discussed, the preferably straight downcomer tube sections 71 extend longitudinally downwardly from the water manifold 46 within the inner shell chamber 67 and inwardly of the shroud member 66, with these tube sec- 5 and 6.

As the straight downcomer tube sections 71 reach their lower extent, they turn laterally outwardly into the involuted tube sections 76, which tube sections 76 extend in involute paths from the downcomer tube sections 71 laterally outwardly to adjacent the shell side wall 23, as best shown in FIG. 7. The involuted tube sections 76 adjacent the shell side wall 23 turn longitudinally upwardly into the involuted serpentine tube sections 77.

As best shown in FIG. 7, the involuted serpentine tube sections 77 not only extend in a progressive laterally inwardly and laterally outwardly or serpentine path pro gressively longitudinally upwardly, but also these tube sections in the laterally inwardly extending portions 88 and laterally outwardly extending portions 96 also extend in involute paths. Thus, the downcomer tube sections 71 form a hollow generally cylindrical tube bundle in the inner shell chamber 67 and the involuted serpentine tube sections 77, with the involuted tube sections 76 and the straight tube sections 91 form a hollow cylindrical tube bundle in the outer shell chamber 68, with this outer tube bundle being telescoped over the inner tube bundle.

Furthermore, with the downcomer tube sections 71 equally spaced and in view of the tubes in the outer shell chamber 68 always extending laterally in involuted paths, despite the extension of the tubes from the inner shell chamber 67 to the outer shell chamber 68 and the serpentine configuration longitudinally upwardly, these tubes will always remain equally spaced. This insures sub stantially equal distribution of fluid within the shell chamber 21 over the tubes of the tube bundle 7th and particu larly the involuted serpentine tube sections 77 in the outer shell chamber 68.

In operation of the heat exchanger construction of the present invention as a steam generator, a heating fluid such as liquid sodium enters the shell inlet connectors 22 and pools around the straight tube sections 91 and over the uppermost of the inner longitudinally extending portions 39 of the involuted serpentine tube sections 77 within the outer shell chamber 68. Since the serpentine portions of these tubes terminate below the shell inlet connectors 22, an even distribution of the shell fluid takes place with this pooling action because there is no appreciable resist ance to the fluid entering the outer shell chamber 68, except very slightly from the straight tube sections 91.

if the serpentine portions of these tubes extended above or laterally in front of the inlet connectors 22, it would be impossible to gain this even distribution, since the tubes of these serpentine portions would cause resistance it) to fluid flow and would cause certain portions of the tubes, particularly those laterally inwardly, to receive little fluid, whereas the outer portions would receive the greater portion of the fluid. Thus, when the particular configuration of tubes shown is provided, an even flow of fluid thereover within the outer shell chamber 68 is insured, and with the laterally involuted paths of the involuted serpentine tube sections 77 resulting in an even spacing at all locations of these tubes, this shell fluid will fiow evenly longitudinally downwardly over the tubes providing a maximum of heat transfer.

This shell fluid ultimately passes longitudinally downwardly through the involuted serpentine tube sections 77 and through the involuted tubes 76, where it passes between the outer and inner supporting rings 98 and 99 and around the spider fingers 34 to the shell lower head 24 Finally, the shell fluid passes out of the shell chamber 21 through the shell outlet connector 25.

Water is admitted through the tube inlet connector 49 and passes into the water mainfold 46, distributing throughout this ring-like water manifold. From water manifold 46, the water passes into the straight downcomer tube sections 77 into the inner shell chamber 67 inwardly of the shroud member 66.

Ultimately, the water passes from the downcomer tube sections 71 into the involuted tube sections 76 and longitudinally upwardly through the involuted serpentine tube sections 77 where the water receives heat from the liquid sodium shell fluid. As the water passes longitudinally upwardly through the involuted serpentine tube sections 77, it is transformed into steam and passes through the straight tube sections 91 into the steam manifold 36 and out through the tube outlet connectors 37 and 38.

During the operation of the heat exchanger, the approximate fluid level of the liquid sodium within the outer shell chamber 68 is indicated by the liquid level line 113. Furthermore, a certain amount of this liquid sodium backs up within the inner shell chamber 67 through the various openings in the members in the lower portion of the inner shell chamber and assumes a level approximately at the liquid level line 11 The portion of the liquid sodium within the inner shell chamber 67 up to the liquid level line 114 remains relatively stationary and stagnant, however, so that there is little heat transfer to the downcomer tube sections 71. Furthermore, the laterally spaced shroud members 65 and 66, forming the separation between the inner and outer shell chambers 67 and 68, prevent the hot liquid sodium in the outer shell chamber 68 from causing the water in the downcomer tube sections 71 to boil prior to reaching the involuted serpentine tube sections 77, so that these shroud members 65 and 66 thereby form an insulating shroud or wall between the inner and outer shell chambers 67 and 68.

When the operation of the heat exchanger construction is interrupted and the flow of liquid sodium stopped, the liquid sodium will assume an approximately equal level in both the inner and outer shell chambers 67 and 68 at approximately the location of the liquid level line 115.

Further, an inert gas blanket is maintained over the liquid sodium filling the remainder of the inner and outer shell chambers 67 and 68 up to the rupture disc 56 at the top of the inner shell chamber 67. This gas blanket can be formed from usual inert gases, such as helium or argon, and has the purpose of providing an insulating blanket over the liquid sodium for protecting the junctions of the tubes with the tube sheets, in the present case such sheets being in the form of the steam and water manifold plates 27 and 40. Thus, this gas blanket serves to eliminate temperature shocks from the junctions of the tubes with the tube sheets.

In view of the opening 79 through the support cylinder 7 8 in the lower portion of the inner shell chamber 67 communicating between the outer and inner shell chambers 68 and 67, the ring-like configurations of the support plates 72 and '75 forming a longitudinally extending openings through the inner shell chamber (67, and the openings 69 in the shroud extension 61 at the upper portion of the outer shell chamber 68 communicating between the outer and inner shell chambers 63 and 67, all portions of the shell chamber 21 are in easy communication with the upper portion of the shell chamber sealed by the rupture disc 55. Thus, if malfunction occurs within the shell chamber 21, whether within the outer shell chamber 68 or within the inner shell chamber 67, the force of any resulting explosion will blow out the rupture disc 56 relieving the pressure of such an explosion and minimizing damage to the remaining parts of the shell 20.

Thus, in the heat exchanger construction of the present invention, due to the involuted and serpentine configuration of the tubes in the tube bundle 7d, a maximum amount of heat transfer area or surface is provided With a minimum of volume of the shell chamber 21. This involuted configuration likewise results in a constant even spacing of all of the tubes in the tube bundle 76 resulting in an equal flow of shell fluid over each of the tubes resulting in the maximum of efficiency for the heat exchanger construction.

Still further, with the involuted serpentine configuration of the tubes in the outer shell chamber 68 ending longitudinally below the shell inlet connectors 22, the shell fluid is permitted to freely enter the shell chamber 21 and pool over the tubes of the tube bundle 70, resul ing in an even distribution of the shell fluid over these tubes and again providing the maximum of efficiency in heat transfer. Still further, in view of the involuted serpentine configuration of the tubes, it is possible to use a minimum number of tubes and tube connections, thereby resulting in less resistance and greater fluid velocity to still again provide a maximum of heat transfer efiiciency.

Also, since separate ring-like inlet and outlet tube sheets in the form of the water manifold plate 40 and steam manifold plate 237 are used, greater inlet and outlet temperature differentials of the fluid within the tube bundle 74) is permitted without setting up damaging stresses in either of these tube sheets or within the tubes. Additionally, since the tube bundle 70 is formed with a bank of tubes extending longitudinally downwardly within the inner shell chamber 67 and then longitudinally upwardly within the outer shell chamber us and with the lowermost portions thereof being relatively free from any solid support, and since the tube bundle is formed with the involuted serpentine tubes '77 relatively loosely supported in the outer and inner support bars 95 and 96, these tubes are, therefore, mounted for relatively free expansion and contraction within the shell chamber 21 and without creating undue stresses therein.

Still further, in view of the relatively direct communication between all portions of the inner and outer shell chambers 67 and 68 with the rupture disc 56 sealing off the upper end of the shell chamber 21, this rupture disc will blow out in the event of malfunction within virtually any portion of the shell chamber 21, thereby minimizing the dangers of such malfunctions critically damaging the major portions of the shell Zll. Finally, in view of the particular construction of the tube bands llld surrounding the tube bundle 7d, the tube bundle may beeasily and conveniently assembled within the shell chamber 21 resulting in a minimum of assembly costs.

Although the particular embodiment of the heat exchanger construction of the present invention is shown with the involuted serpentine tube sections 77 in the outer shell chamber 68 and the downcomer tube sections 71 in the inner shell chamber 67, it should be understood that these tube sections can be otherwise positioned without departing from the principles of the present invention. For instance, the involuted serpentine tube sections could be in the inner shell chamber and the downcomer tube sections in the outer shell chamber, with the water and steam manifolds reversed and the liquid sodium admitted 12 to the inner shell chamber flowing over these involuted serpentine tube sections, to thereby gain the main portion of the advantages of the present invention.

In the foregoing description, certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom, because such words are used for descriptive purposes herein and are intended to be broadly construed.

Moreover, the embodiment of the improved construction illustrated and described herein is by way of example, and the scope of the present invention is not limited to the exact details of the construction shown.

Having now described the invention, the construction, operation and use of a preferred embodiment thereof, and the advantageous new and useful results obtained thereby; the new and useful construction and reasonable mechanical equivalents thereof obvious to those skilled in the art are set forth in the appended claims.

We claim:

1. Heat exchanger construction including a heat exchanger shell forming a shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, tube sheet means connected to the shell, a tube bundle connected to the tube sheet means and extending generally longitudinally within the shell chamber, the tube bundle having a series of substantially uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced generally longitudinally in a first bank of tube sections and then substantially uniformly spaced i1 involute paths laterally and then substantially uniformly spaced in combined involute lateral and serpentine paths forming at least a substantial part of a second bank of tube sections extending generally longitudinally back to the tube sheet means, the involute lateral and serpentine part of the second bank of tube sections extending progressively generally laterally in one general direction in involute paths and then generally longitudinally and then generally laterally in involute paths in a direction generally opposite from said one direction while the tubes in said second bank remain substantially uniformly spaced throughout said second bank, and all of the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows.

2. Heat exchanger construction including a heat exchanger shell forming a shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, tube sheet means connected to the shell, a tube bundle connected to the tube sheet means and extending generally longitudinally within the shell chamber, the tube bundle having a series of substantially uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced straight generally longitudinally in a first bank of straight tube sections and then substantially uniformly spaced in involute paths laterally and then substantially uniformly spaced in combined involute lateral and serpentine paths forming at least a substantial part of a second bank of tube sections extending generally longitudinally back to the tube sheet means, the involute lateral and serpentine part of the second bank of tube sections extending progressively generally laterally in one direction in involute paths and then generally longitudinally and then generally laterally in involute paths in a direction generally opposite from said one direction while the tubes in said second bank remain substantially uniformly spaced throughout said second bank, and all of the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows.

3. Heat exchanger construction including a heat exchanger shell forming a shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, tube sheet means connected to the shell, a hollow generally cylindrical tube bundle connected to the tube sheet means and extending generally longitudinally within the shell chamber, the tube bundle having a series of substantially uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced generally longitudinally in a first hollow generally cylindrical bank of tube sections and then substantially uniformly spaced in involute paths laterally and then substantially uniformly spaced in combined involute lateral and serpentine paths forming at least a substantial part of a second hollow generally cylindrical bank of tube sections extending generally longitudinally back to the tube sheet means, one of said first and second banks of tube sections being positioned telescoped laterally surrounding the other of said banks of tube sections with the tubes extending substantially uniformly spaced in said involute paths laterally between said banks of tube sections spaced longitudinally from the tube sheet means, the involute lateral and serpentine part of the second bank of tube sections extending progressively generally laterally in one general direction in involute paths and then generally longitudinally and then generally laterally in involute paths in a direction generally opposite from said one direction While the tubes in said second bank remain substantially uniformly spaced throughout said second bank, and all of the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows.

4. Heat exchanger construction including a generally vertically extending heat exchanger shell forming a generally vertically extending shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, generally horizontally extending tube sheet means connected to the shell, a tube bundle connected to the tube sheet means and extending generally vertically downwardly within the shell chamber, the tube bundle having a series of substantially uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced generally vertically downwardly in a first bank of tube sections and then substantially uniformly spaced in involute paths horizontally and then substantially uniformly spaced in combined involute horizontal and serpentine paths forming a part of a second bank of tube sections which second bank of tube sections extends generally vertically upwardly to the tube sheet means, the involute horizontal and serpentine part of the second bank of tube sections extending progressively gen erally horizontally in one general direction in involute paths and then generally vertically upwardly and then generally horizontally in involute paths in a direction generally opposite from said one direction while the tubes in said second bank remain substantially uniformly spaced throughout said second bank, the involute horizontal and serpentine paths of said second bank of tube sections terminating spaced vertically downwardly from the tube sheet means and extending vertically upwardly to said tube sheet means in the form of substantially uniformly spaced generally vertically extending tube sections, the shell fluid inlet means being horizontally aligned with at least a portion of said substantially uniformly spaced vertically extending tube sections in said second bank for directing shell fluid in a direction horizontally toward the vertically extending tube sections of said second bank so that the shell fluid may flow horizontally over said vertically extending tube sections of said second bank and then substantially uniformly vertically downwardly over the combined involute horizontal and serpentine second bank of tube sections, and all or" the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows.

5. Heat exchanger construction including a generally vertically extending heat exchanger shell forming a generally vertically extending shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, generally horizontally extending tube sheet means connected to the shell, a hollow generally cylindrical tube bundle connected to the tube sheet means and extending generally vertically downwardly within the shell chamber, the tube bundle having a series of uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced generally vertically downwardly in a first hollow generally cylindrical bank of tube sections and then substantially uniformly spaced in involute paths horizontally and then substantially uniformly spaced in combined involute horizontal and serpentine paths forming a part of a second hollow generally cylindrical bank of tube sections which second bank of tube sections extends generally vertically upwardly to the tube sheet means, one of said first and second banks of tube sections being positioned telescoped horizontally surrounding the other of said banks of tube sections with the substantially uniformly spaced tubes extending in said involute paths horizontally between said banks of tube sections spaced vertically downwardly from the tube sheet means, the involute horizontal and serpentine part of the second bank of tube sections extending progressively generally horizontally in one general direction in involute paths and then generally vertically upwardly and then generally horizontally in involute paths in a direction generally opposite from said one direction while the tubes in said second bank remain substantially uniformly spaced throughout said second bank, the involute horizontal and serpentine paths of said second bank of tube sections terminating spaced vertically downwardly from the tube sheet means and extending vertically upwardly to said tube sheet means in the form of substantially uniformly spaced generally vertically extending tube sections, the shell fluid inlet means being horizontally aligned with at least a portion of said substantially uniformly spaced vertically extending tube sections in said second bank for directing shell fluid in a direction horizontally toward the vertically extending tube sections of said second bank so that the shell fluid may flow horizontally over said vertically extending tube sections of said second bank and then substantially uniformly vertically downwardly over the combined involute horizontal and serpentine second bank of tube sections, and all of the portions of the tube sec tions in at least the second bank which extend longitudinally being positioned in laterally involute rows.

6. Heat exchanger construction including a generally vertically extending heat exchanger shell forming a generally vertically extending shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, generally horizontally extending tube sheet means connected to the shell, a hollow generally cylindrical tube bundle connected to the tube sheet means and extending generally vertically downwardly within the shell chamber, the tube bundle having a series of uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced straight generally vertically downwardly in a first hollow generally cylindrical bank of straight downcomer tube sections and then substantially uniformly spaced in involute paths horizontally and then substantially uniformly spaced in combined involute horizontal and serpentine paths forming a part of a second hollow generally cylindrical bank of tube sections which second bank of tube sections extends generally vertically upwardly to the tube sheet means, one of said first and second banks of tube sec tions being positioned telescoped horizontally surrounding the other of said banks of tube sections with the substantially uniformly spaced tubes extending in said involute paths horizontally between said banks of tube sections spaced vertically downwardly from the tube sheet means, the involute horizontal and serpentine part of the second bank of tube sections extending progressively generally horizontally in one general direction in involute paths and then generally vertically upwardly and then generally horizontally in involute paths in a direction generally opposite from said one direction while the tubes in said second bank remain substantially uniformly spaced throughout "said second bank, the involute horizontfl and serpentine paths of said second bank of tube sections termina.'ng spaced vertically downwardly from the tube sheet means and extending vertically upwardly to said tube sheet means in the form of substantially uniformly spaced straight generally vertically extending tube sections, the shell fluid inlet means being horizontally aligned with and horizontally spaced from at least a portion of said substantially uniformly spaced straight tube sections in said second bank for directing shell fluid in a direction horizontally toward the straight tube sections of said second bank so that the shell fluid may flow horizontally over said straight tube sections of said second bank and then substantially uniformly vertically downwardly over the combined involute horizontal and serpentine second bank of tube sections and all of the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows.

7. Heat exchanger construction including a generally vertically extending heat exchanger shell forming a generally vertically extending shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, generally horizontally extending tube sheet means connected to the shell, a hollow generally cylindrical tube bundle connected to the tube sheet means and extending generally vertically downwardly within the shell chamber, the tube bundle having a series of substantially uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced straight generally vertically downwardly in a first hollow generally cylindrical bank of straight downcomer tube sections and then substantially uniformly spaced in involute paths horizontally outwardly forming bank connecting tube sections and then substantially uniformly spaced in combined involute horizontal and serpentine paths forming a part of a second hollow generally cylindrical bank of tube sections which second bank of tube sections extends generally vertically upwardly to the tube sheet means, the second bank of tube sections being positioned telescoped horizontally surrounding the first bank of tube sections with the substantially uniformly spaced tubes extending in said involute paths horizontally between said banks of tube sections spaced vertically downwardly from the tube sheet means, a vertically extending hollow generally cylindrical insulating wall supported in the shell chamber extending from said bank connecting tube sections substantially to the tube sheet means around the first bank of tube sections and between the first and second banks of tube sections shielding said first bank from said second bank, the involute horizontal and serpentine part of the second bank of tube sections extending progressively generally horizontally in one general direction in involute paths and then generally vertically upwardly and then generally horizontally in involute paths in a direction generally opposite from said one direction while the tubes in said second bank remain substantially uniformly spaced throughout said second bank, the involute horizontal and serpentine paths of said second bank of tube sections terminating spaced vertically downwardly from the tube sheet means and extending vertically upwardly to said tube sheet means in the form of substantially uniformly spaced straight generally vertically extending tube sections, the shell fluid inlet means being horizontally aligned with and horizontally spaced from at least a portion of said straight vertical tube sections in said second bank for directing shell fluid in a direction horizontally toward said straight tube sections of said second bank so that the shell fluid may flow horizontally over said vertically extending tube sections of said second bank and then substantially uniformly vertically downwardly over the combined involute horizontal and serpentine second bank of tube sections, and all of the portions of the tube sections in at least the second bank teases.

which extend longitudinally being positioned in laterally involute rows.

8. Heat exchanger construction including a heat ex change shell forming a shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, tube sheet means connected to the shell, a hollow generally cylindrical tube bundle connected to the tube sheet means and extending generally longitudinally within the shell chamber, the tube bundle having a series of substantially uniformly spaced tubes, the tubes extending from the tube sheet means substan tially uniformly spaced generally longitudinally in a first hollow generally cylindrical bank of tube sections and then substantially uniformly spaced in involute paths laterally outwardly and then substantially uniformly spaced in combined involute lateral and serpentine paths forming at least a substantial part of a second hollow generally cylindrical bank of tube sections extending generally longitudinally back to the tube sheet means, the second bank of tube sections being positioned telescoped laterally surrounding the first bank of tube sections with the tubes extending in said involute paths substantially uniformly spaced laterally outwardly between said banks of tube sections spaced longitudinally from the tube sheet means, the involute lateral and serpentine part of the second bank of tube sections extending progressively generally laterally in one general direction in involute paths and then generally longitudinally and then generally later-ally in involute paths in a direction generally opposite from said one direction while the tubes in said second bank remain substantially uniformly spaced throughout said second bank, and all of the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows.

9. Heat exchanger construction including a generally vertically extending heat exchanger shell forming a generally vertically extending shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, generally horizontally extending tube sheet means connected to the shell, a hollow generally cylindrical tube bundle connected to the tube sheet means and extending generally vertically downwardly within the shell chamber, the tube bundle having a series of uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced straight generally vertically downwardly in a first hollow generally cylindrical bank of straight downcomer tube sections and then substantially uniformly spaced in involute paths horizontally outwardly forming bank connecting tube sections and then substantially uniformly spaced in combined involute horizontal and serpentine paths forming a part of a second hollow generally cylindrical bank of tube sections which second bank of tube sections extends generally vertically upwardly to the tube sheet means, the second bank of tube sections being positioned telescoped horizontally surrounding the first bank of tube sections with the substantially uniformly spaced tubes forming said bank connecting tube sections extending in said involute paths horizontally outwardly between said banks of tube sections spaced vertically downwardly from the tube sheet means, the involute horizontal and serpentine part of the second bank of tube sections extending progressively generally horizontally in one general direction in involute paths and then generally vertically upwardly and then generally horizontally in involute paths in a direction generally opposite from said one direction while the tubes in said second bank remain substantially uniformly spaced throughout said second bank, the involute horizontal and serpentine paths of said second bank of tube sections terminating spaced vertically downwardly from the tube sheet means and extending vertically upwardly to said tube sheet means in the form of substantially uniformly spaced straight generally vertically extending tube sections, the shell fluid inlet means being horizontally aligned with and horizontally spaced from at least a portion of said substantially uniformly spaced straight tube sections in said second bank for directing shell fluid in a direction horizontally toward the straight tube sections of said second bank so that the shell fluid may flow horizontally over said straight tube sections of said second bank and then substantially uniformly vertically downwardly over the combined involute horizontal and serpentine second bank of tube sections, and all of the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows.

10. Heat exchanger construction including a heat eX- changer shell forming a shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, tube sheet means connected to the shell, a tube bundle connected to the tube sheet means and extending generally longitudinally Within the shell chamber, the tube bundle having a series of substantially uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced generally longitudinally in a first bank of tube sections and then substantially uniformly spaced in involute paths laterally and then substantially uniformly spaced generally longitudinally in a second bank of tube sections extending generally longitudinally back to the tube sheet means, and all of the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows.

11. Heat exchanger construction including a heat exchanger shell forrning a shell chamber and having fluid inlet means and fluid outlet means communicating with said shell chamber, tube sheet means connected to the shell, a hollow generally cylindrical tube bundle connected to the tube sheet means and extending generally longitudinally within the shell chamber, the tube bundle having a series of substantially uniformly spaced tubes, the tubes extending from the tube sheet means substantially uniformly spaced generally longitudinally in a first hollow generally cylindrical bank of tube sections and then substantially uniformly spaced in involute paths laterally and then substantially uniformly spaced generally longitudinally forming a second hollow genenally cylindrical bank of tube sections extending generally longitudinally back to the tube sheet means, one of said first and second banks of tube sections being positioned telescoped laterally surrounding the other of said banks of tube sections with the tubes extending substantially uniformly spaced in said involute paths laterally between said banks of tube sections spaced longitudinally from the tube sheet means, all of the portions of the tube sections in at least the second bank which extend longitudinally being positioned in laterally involute rows, and each of the lateral rows of tube section portions in both the first and second banks which extend longitudinally having the same number of said tube section portions.

References Cited in the file of this patent UNITED STATES PATENTS 1,737,712 Gazelle Dec. 3, 1929 1,818,446 Armacost Aug. 11, 1931 1,955,006 I-Iateer et a1. Apr. 17, 1934 2,064,901 Fletcher Dec. 22, 1936 2,088,456 Wood July 27, 1937 2,402,881 Fausek et a1. June 25, 1946 2,662,749 Buschow Dec. 15, 1953 2,670,185 Schorner et al. Feb. 23, 1954 2,774,575 Walter Dec. 18, 1956 2,920,873 Schluderberg et a1. Ian. "12, 1960 

1. HEAT EXCHANGER CONSTRUCTION INCLUDING A HEAT EXCHANGER SHELL FORMING A SHELL CHAMBER AND HAVING FLUID INLET MEANS AND FLUID OUTLET MEANS COMMUNICATING WITH SAID SHELL CHAMBER, TUBE SHEET MEANS CONNECTED TO THE SHELL, A TUBE BUNDLE CONNECTED TO THE TUBE SHEET MEANS AND EXTENDING GENERALLY LONGITUDINALLY WITHIN THE SHELL CHAMBER, THE TUBE BUNDLE HAVING A SERIES OF SUBSTANTIALLY UNIFORMLY SPACED TUBES, THE TUBES EXTENDING FROM THE TUBE SHEET MEANS SUBSTANTIALLY UNIFORMLY SPACED GENERALLY LONGITUDINALLY IN A FIRST BANK OF TUBE SECTIONS AND THEN SUBSTANTIALLY UNIFORMLY SPACED IN INVOLUTE PATHS LATERALLY AND THEN SUBSTANTIALLY UNIFORMLY SPACED IN COMBINED INVOLUTE LATERAL AND SERPENTINE PATHS FORMING AT LEAST A SUBSTANTIAL PART OF A SECOND BANK OF TUBE SECTIONS EXTENDING GENERALLY LONGITUDINALLY BACK TO THE TUBE SHEET MEANS, THE INVOLUTE LATERAL AND SERPENTINE PART OF THE SECOND BANK OF TUBE SECTIONS EXTENDING PROGRESSIVELY GENERALLY LATERALLY IN ONE GENERAL DIRECTION IN INVOLUTE PATHS AND THEN GENERALLY LONGITUDINALLY AND THEN GENERALLY LATERALLY IN INVOLUTE PATHS IN A DIRECTION GENERALLY OPPOSITE FROM SAID ONE DIRECTION WHILE THE TUBES IN SAID SECOND BANK REMAIN SUBSTANTIALLY UNIFORMLY SPACED THROUGHOUT SAID SECOND BANK, AND ALL OF THE PORTIONS OF THE TUBE SECTIONS IN AT LEAST THE SECOND BANK WHICH EXTEND LONGITUDINALLY BEING POSITIONED IN LATERALLY INVOLUTE ROWS. 